The invention relates to a wiper arm.
Known windshield wipers have a wiper arm that is comprised of a mounting part and an articulating part pivotably connected to it, which has a wiper rod. The wiper rod has a wiper blade pivotably connected to it, which is comprised of a wiper strip and a support bracket system with a primary center bracket and pivotably connected secondary intermediate brackets and claw brackets.
The articulating part has a spring chamber for a tension spring at its end oriented toward the mounting part. The spring chamber is open toward the vehicle windshield and has a slot-shaped extension, which is oriented toward the wiper rod and has a first anchor point on which a securing bracket of the tension spring is suspended. The other end of the tension spring is provided with a C-shaped bracket, which is suspended on a suspension device of the, mounting part; this suspension device serves as the second anchor point. The articulating part is also supported by means of a hub on a bolt-shaped hinge pin, which is disposed in a first region of the mounting part oriented toward the articulating part. The joint thus produced, also called a hinge joint, and the suspension device of the tension spring, are disposed in relation to each other so that the tension spring pulls the articulating part and the wiper rod with the wiper blade toward a vehicle windshield.
The articulating part of the windshield wiper is folded away from the vehicle windshield for cleaning or installation of the wiper blade. To this end, the articulating part is pivoted around the hinge pin of the hinge joint, during which the tension spring assumes a position in which it pulls the articulating part against a stop, which is supported on the mounting part and limits the pivoting motion.
A second region of the mounting part is mounted on the free end of a drive shaft, which is supported in a wiper bearing and driven by a wiper motor by means of a crank and a rod assembly. The wiper motor is held in place by a mounting plate, which is mounted on the vehicle body and which contains wiper bearings. Frequently, the wiper bearings themselves serve as anchor points by passing through openings in the vehicle body and being screwed into the vehicle body with the interposition of vibration-damping rubber elastic elements.
The end of the drive shaft protruding from the vehicle body represents a significant danger source for injuries during accidents with pedestrians. With regard to accidents with pedestrians, European Commission outlines for crash regulations (EC III/5021/96 EN) define maximum acceleration values, so called head injury criteria, in the vicinity of the vehicle hood and the wiper system. These criteria cannot be met with conventional wiper systems, even if the vehicle hood overlaps the drive shaft, because in this case, too, there is no assurance that the vehicle hood and the drive shaft are far enough apart, particularly with tight hood clearances.
One possible solution for this is to shift the end of the drive shaft further into the engine compartment. Vehicle manufacturers require a minimum distance of 65-85 mm between vehicle hood and the end of the drive shaft. This also increases the distance from this drive shaft end to the articulating part, requiring a longer mounting part. Besides, at least during wiping, the mounting part still protrudes into the region a pedestrian would strike during impact.
A wiper system with a moveable drive shaft is disclosed in DE 198 03 344 A1. According to this reference, the protruding end of the drive shaft is shifted into the vehicle body when an axial force of a predetermined magnitude acts on the end of the drive shaft from the outside. In order to cushion the impact, means are provided between an inwardly oriented stop of the drive shaft and a part permanently connected to the vehicle body or between such a part and the vehicle body; these means plastically and/or elastically deform when acted on in the axial direction by a critical axial force, causing the end of the drive shaft to move into the engine compartment in a defined manner. These means can be comprised of a plastically deformable sheet metal sleeve, which suitably has a region that is corrugated in the axial direction of the axis, or can be comprised of thin-walled, disk-shaped elements, which, depending on the displacement distance, can be disposed operatively in series. These elements can have such a small amount of play in relation to the drive shaft or to other adjacent components that when they deform, they come into contact with these components and through friction, increase the cushioning action. Finally, the means can be disposed so that they are compressed or stretched apart when subjected to the critical axial force. The drive shaft can also be axially secured to the bearing housing of the wiper bearing by means of form-fitting elements with a predetermined breaking point, which break or bend into available space when subjected to a critical axial force. Predetermined breaking points of this kind can be created by means of notches, bores, or shearing pins. Aside from the fact that some embodiments of this principle are very complex structurally, the principle is also only effective if the impact occurs in the vicinity of the end of the drive shaft.